Effect of Root Pruning on Growth and Fruiting of Peach Trees

The effect of root pruning on growth and fruit quality of ‘Yumyung’ peach trees was determined over multiple years. The trees used were 10 year-old and vegetatively excessive in the high-density orchard system. The trees were root-pruned at both sides of the tree at a distance of 50, 100 or 150cm from the trunk, all at 30cm in depth. The determination of the pattern of root distribution showed that more than 97% of the roots were remained within 150cm from the trunk, while 76% of the total roots were remained within 50cm from the trunk and 91% within 100cm. As for vertical root distribution, more than 90% of the roots were remained in the soil of 50cm in depth, while 54% in 30cm and 81% in 40cm in depth. Root pruning decreased the number of new shoots; with the root pruning practiced closer to the trunk being more effective. Root pruning significantly increased the level of PAR (Photosynthetic Active Radiation) in the canopy compared to no root pruning. Fruit size, especially diameter, were reduced by root pruning; the extent of size reduction was negatively correlated with the pruning distance from the trunk, and this effect was more obvious in the 2nd and 3rd year after root pruning than the 1st year. Yield was also reduced by root pruning significantly in the 50cm distance treatment in the 1st and 2nd year after root pruning. The amount of winter pruning was reduced by root pruning. It was concluded that root pruning in 50cm distance from the trunk was rather severe in terms of substantial reduction of vegetable growth, yield, and fruit size. The root pruning at a distance of 150cm showed its effect in the 1st year but disappeared in the 3rd year. The root pruning at 100cm proved to be the best treatment in terms of a reduction of vegetative growth without negative effects on fruit quality characteristics, while the effect remained for three years.